1. Field of the Invention
The present invention relates to an exhaust gas recirculation system, and more particularly to an exhaust gas recirculation system with a unified cylinder head and exhaust gas recirculation device.
2. Description of Related Art
Recently, a method that recirculates a portion of exhaust gas to an intake passage in order to reduce NOx of the exhaust gas has been proposed.
Particularly, an exhaust gas recirculation system provided with an exhaust gas recirculation valve (hereinafter called an EGR valve) disposed at one side of an intake manifold disposed between two cylinder banks is well known.
The exhaust gas recirculation system indicates such a method that the recirculation gas is flowed into each inflow ports from passages formed at the intake manifolds through the intake passage therein, or a recirculation gas is flowed into the intake port from the exhaust gas port to the intake port in a long distance.
Performance of an internal combustion engine of a lean combustion type depends on responsiveness of the exhaust gas recirculation.
However, due to the long distance between the exhaust port and the intake port, the responsiveness thereof needs to be improved.
Meanwhile, a material or layout for it is limited because a passage should be considered so that it can guide the exhaust gas to the intake manifold.
Further, a pipe for guiding the exhaust gas from the cylinder head to the intake manifold should be assembled separately, and so the number of parts is increased, and it also requires a space for assembling the pipe.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.